Solid oxide fuel cell (SOFC) is one of the most promising next-generation electrochemical energy conversion devices because of its wide choice of fuels, cleanliness and, high efficiency of up to 70-85%( with heat utilization). Recently, low-temperature SOFC (< 600 ℃) has been studied to overcome the limitations of conventional SOFC, e.g., thermal stability, cost, and limited application. However, lowering operated temperature is challenging due to slow charge transfer and ion transport rates. Therefore, SOFC design with thin-film stacks, namely thin-film SOFC (TF-SOFC) fabricated on porous anode support, have been usually adopted for sufficient power density even at this temperature regime.

A ceramic-metal composite (cermet) of Ni and YSZ (yttria-stabilized zirconia) is the most common anode or anode functional layer (AFL) material of TF-SOFC, because Ni-YSZ cermet has reasonable cost, chemical stability in a reducing atmosphere at high temperature, and similar thermal expansion coefficient to that of YSZ electrolyte. Various thin-film techniques have been reported for AFL fabrication, e.g., pulsed laser deposition (PLD), RF sputtering, etc. Among those, reactive sputtering method, which uses metal target in controlled gas conditions (e.g., oxygen condition for oxide deposition), is a versatile method to deposit various types of thin films with fast deposition speed (up to > 1um/hr), which is beneficial in manufacturability regarding the usual thickness range of AFL (a few microns).

In this study, therefore, we studied physical and chemical properties of nanocomposite Ni-YSZ films fabricated by using the reactive sputtering deposition technique, focusing on the effect of sputter parameters. In particular, Oxygen partial pressure significantly affects deposition speed, surface morphology, composition, electrochemical performance, and thermal durability at 450 ℃. It is shown that excessive O₂/Ar partial pressure ratio (> 0.2) significantly reduces the deposition speed by approximately one order of magnitude compared to the lower ratio case. In morphological analysis, O2/Ar partial pressure ratio affect nano-structured of anode, after annealing process at 1200℃ with air. Also, the Ni-YSZ anode sputtered at the environment of O₂/Ar partial pressure ratio of 0.1 sample shows the lowest activation resistance when applied to LT-SOFC’s anode. The O₂/Ar 0.5 sample shows surface Ni agglomeration due to high NiO-to-metallic Ni ratio.